The INFINITY BUG is connected across the phone-line of a distant phone
(in parallel mode). To use the Bug, the distant phone is rung. After
having a conversation with the person at the other end, they will
replace the receiver. At this point you whistle into the receiver and
the Infinity Bug will pick up the line. The high-gain amplifier in the
Infinity Bug will pick up the audio at the place where it is located.
It does not have to be next to the distant phone. It can be anywhere,
provided it is connected across the phone line of the distant phone. A
timing circuit in the device will cancel after 3 minutes. To open the
Bug you need to whistle again. This can be repeated any number of
times.
If the phone is picked up, it cancels the Bug.